2019 in space: 25 notable astronomy discoveries in the last year
Right now, dozens of instruments, rovers, satellites, telescopes, probes, explorers, and other astonishing technological wonders are floating through space, taking pictures, collecting samples, and even driving around on other planets. Few scientific fields have grown more rapidly and more impressively in the last few decades than the field of astronomy. The branch of science that deals with space, the physical universe, and its many celestial objects is enjoying a golden age right now, with astonishing discoveries piling up every month—and for astronomers, 2019 was a banner year.
Astronomers and other scientists made discoveries in 2019 that test the limits of the human imagination. From star-eating black holes hundreds of millions of light-years away to too-close-for-comfort asteroids hurtling dangerously close to our planet, some of these discoveries were difficult to comprehend even for the scientists who made them. The year 2019 revealed dead stars that are so big they shouldn’t be able to exist, massive ice stores hidden beneath the surface of Mars, and entire galaxies that date back billions of years to the earliest moments of the universe’s birth. Some discoveries will change how scientists collect data, add new pieces to puzzles that have baffled scientists for generations, or help astronomers protect their equipment in space. Other discoveries don’t have any immediate practical applications but are simply so cool that they made headlines around the world.
Stacker consulted numerous astronomy publications, journals, and news sources to find the 25 most notable discoveries or advancements in the field of astronomy in 2019. Some were made by elite scientists at NASA, others by amateurs with their own equipment. Some were made at universities, others were made by man-made machines racing through the cosmos billions of miles away. All, however, are so impressive that they boggle the minds of human beings attempting to contemplate the vast, complex, and mysterious world of outer space.
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The sun’s new activity
In 2019, instruments on NASA’s Parker Solar Probe relayed some surprising information to scientists back on Earth. The probe found that energetic particles emanating from the sun are much more varied and numerous than previously thought. It’s important information, which could help scientists predict the kind of solar storms that can disrupt space communications equipment.
Saturn’s new moons
In October 2019, astronomers announced that they had discovered 20 previously unknown moons orbiting Saturn. That brought the number of the planet’s known satellites to 82.
Impossible black hole
At the end of November, astronomers announced the discovery of a black hole so massive, so enormous, that it shouldn’t be able to exist. This stellar black hole—which forms when dead stars collapse and explode—has a mass 70 times greater than the sun. It was previously believed that black holes could grow to only 20 times the size of the sun’s mass.
Black hole triplets
In 2019, a well-known galaxy merger called NGC 6240 revealed a secret. Scientists found three supermassive black holes sharing space in surprisingly tight quarters. In one of the rarest occurrences in the known universe, the composition of NGC 6240 was visibly disturbed by the incomprehensible tug of gravity generated by the trio.
Around the end of 2018, NASA’s OSIRIS-REx mission arrived at its destination—an active near-Earth asteroid called Bennu. On Jan. 19 and Feb. 19, 2019, astronomers discovered that the top-shaped asteroid was “active,” ejecting rocks and other particles in plumes, with some particles falling and landing back on the asteroid and others getting trapped in its gravitational orbit. It was the first observation of a rock-ejecting asteroid.
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Where’s the matter?
In one of the odder discoveries of the year, scientists identified 19 previously unknown dwarf galaxies—but that’s not the strangest part. All 19 were missing dark matter, the mysterious, invisible mass that emits no light but exerts a gravitational pull. Scientists have no idea why the new galaxies are void of dark matter or how a galaxy could exist without it.
Record-breaking neutron star
Neutron stars are dead stars that met their fate in gigantic explosions called supernovas, and while researchers have long known about them, astronomers have never found one quite as massive as the one they discovered in 2019. Small but extremely dense, neutron stars usually measure only about 12 miles in diameter, but they can have a mass of 100 million tons. This one measures 15 miles in diameter but has a mass 2.14 times greater than that of the sun, which is so massive that scientists previously thought such a find to be impossible.
[Pictured: A pulsar, a fast-rotating neutron star.]
In 2019, Earth’s solar system received a visitor. A comet from a different solar system—the second one in two years—made a grand entry into Earth’s planetary ecosystem, and no one knows where it came from or how it got here. Called C/2019 Q4, it was first discovered by an amateur astronomer in Crimea named Gennady Borisov.
[Pictured: At center, the Comet C/2019 Q4 as imaged by the Canada-France-Hawaii Telescope on Hawaii's Big Island on Sept. 10, 2019.]
A giant, ancient galaxy
University of Arizona astronomer Christina Williams noticed a strange glob of light resonating from her instruments one day in 2019—and it turned out to be one of the biggest discoveries of the year. Scientists believe that the light she saw began its journey 12.5 billion years ago from one of the biggest and earliest galaxies in the universe’s history. The previously invisible galaxy gives scientists a glimpse into the infancy of the universe.
[Pictured: One of the most massive known galaxy clusters, RX J1347.5–1145, the center of which shows up here in the dark “hole” in the ALMA observations.]
Three nearby earthly mimics
Also in 2019, scientists at the Institute of Space Sciences in Barcelona, Spain, reported finding three Earth-sized planets orbiting a red dwarf star just 12 light-years away—right around the corner in interstellar geography terms. The researchers believe one of them might have the right conditions to possibly support life.
[Pictured: This artist's concept illustrates a young, red dwarf star surrounded by three planets.]
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